GUARANTEE Synonyms: 101 Similar and Opposite Words - Merriam-Webster
https://www.merriam-webster.com/thesaurus/guarantee
WebSynonyms for GUARANTEE: bond, assure, guaranty, certify, pledge, warrant, contract, undertake; Antonyms of GUARANTEE: undermine, weaken, enfeeble, minimize, ignore, disregard, understate, neglect
DA: 57 PA: 81 MOZ Rank: 77